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| Titel |
Tropospheric chemistry of emissions from the Antarctic volcano, Mt. Erebus |
| VerfasserIn |
C. Oppenheimer  , D. Davis, P. Kyle |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250025716
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| Zusammenfassung |
| We report here measurements of gaseous species in the plume emitted by Erebus volcano,
Antarctica, made during the austral summer of 2005. The first set of observations was
recorded using a Twin Otter instrumented aircraft, which intercepted the plume at variable
distances (up to 56 km) from the active crater. The second set of measurements was made by
open-path infrared absorption spectroscopy with an FTIR instrument positioned on the crater
rim. The airborne measurements sampled the plume up to 9 h in age, while the ground-based
observations pertain to emissions less than 1 min after their release from the active lava lake
contained in the crater. The species CO, OCS and SO2 were measured using both air and
ground based instruments. These observations revealed that, while CO and OCS
were conserved in the plume during atmospheric transport, the abundance of SO2
relative to CO was found to be lower by approximately two-thirds beyond the crater
rim. However, over the entire length of the directly sampled plume, the ratio of
CO:SO2, did not significantly change. The airborne instrumentation also yielded
further observations of volcanogenic H2SO4 and HNO3 as well as the first volcanic
plume observations of the trace gas species, HO2NO2. Interestingly, no NOx was
present. Since NO2 has previously been detected in the proximal Erebus plume, we
conclude that NOx was quickly oxidized to nitric and pernitric acid, and probably
nitrate in the aerosol phase. It is also possible that this occurred in tandem with the
conversion of SO2 to sulfate. If true, one can speculate that rapid heterogeneous
chemical processes occurred by “cloud-processing” in an early stage of the plume’s
evolution in which liquid phase aerosol was abundant. In plumes older than about 4 h,
we also report substantial ozone depletion, leading to the hypothesis that other
nitrogen species were produced in the crater, which contain chlorine and bromine.
We further speculate that the photolysis of these halo-nitrates could then release
reactive halogens that would lead to O3 depletion in air entrained into the plume. |
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